1. Field of the Invention
The present invention relates to a photographing optical lens assembly, and more particularly, to a compact photographing optical lens assembly used in a mobile phone camera.
2. Description of the Prior Art
In recent years, with the popularity of mobile phone cameras, the demand for compact imaging lenses is increasing, and the sensor of a general photographing camera is none other than CCD (charge coupled device) or CMOS device (Complementary Metal Oxide Semiconductor device). Furthermore, as advanced semiconductor manufacturing technology has allowed the pixel size of sensors to be reduced and electronic devices have become more compact and powerful, there is an increasing demand for compact imaging lenses featuring better image quality.
A conventional compact imaging lens generally comprises two lens elements so as to reduce the production cost. As the two-element lens has limited capability to correct aberrations, it became insufficient for a high-end photographing module. However, employing excess number of lens elements will make it difficult to reduce the total track length of the lens.
To obtain good image quality and maintain a compact form, a photographing optical lens assembly comprising three lens elements is a feasible solution. The optical lens system for taking image disclosed in U.S. Pat. No. 7,436,603 is of a triplet type comprising, in order from the object side to the image side: a first lens element with positive refractive power; a second lens element with negative refractive power; and a third lens element with positive refractive power. Though such an arrangement facilitates the correction of most of the aberrations caused by the optical system, it requires a longer total track length, and thus the size of the optical lens system for taking image must increase to accommodate the lengthened total track length. Consequently, the optical lens system for taking image is unable to maintain a compact form.
Therefore, a need exists in the art for a photographing optical lens assembly that features better image quality, maintains a moderate total track length and is applicable to compact portable electronic products.